Brake calipers quality

[lenny]

 

[saneagle]

Very interesting post. How thin should I allow a rim to get, before changing it?

Most rims have a black line in the middle of the brake contact area all round the rim on both sides. The line indicates the wear. When it's worn through, it's time to replace the rim. It assumes that your brakes are rubbing on that area correctly. Excess wear on the outer edge next to the tyre is not such a problem, but excess wear on or near the other edge causes the rim to detach.

If your rim never had the wear lines, you'd have to measure the thickness with some sort of thickness measuring device.

 

[AndyBike]

If your rim never had the wear lines, you'd have to measure the thickness with some sort of thickness measuring device.

You can gauge roughly by putting a steel ruler across the rim braking surface and seeing how much of a concave it has.

 

[chris667]

See, I'm right. I knew you'd eventually agree.

i have absolutely no idea what you're talking about. But thanks for your contribution.

 

[chris667]

Current Clarks brakes I have adjustment screw (tension) all the way in on one side and fully out on the other which is odd but they are balanced. I'm not happy with that. I adjust every couple of weeks.

As a rule of thumb, always try to remove the tension by backing the screws off. Less tension on the arms is usually better than adding tension. In practice it doesn't really matter if they aren't dead centre.

Re rim wear, almost all modern rims have an indicator. I think this thread might make you worry more about that than you need to. Rims are consumables.

 

[AndyBike]

 

[AndyBike]

https://www.retrobike.co.uk/gallery2/d/78783-2/Kona+1996+cat+_2_.pdf

And of course one of the most iconic bikes in MTBing history, the Pace RC100
As originally specced with Maguras.

 

[saneagle]

https://www.retrobike.co.uk/gallery2/d/78783-2/Kona+1996+cat+_2_.pdf

And of course one of the most iconic bikes in MTBing history, the Pace RC100
As originally specced with Maguras.
View attachment 55874

No good for conversion without disc brakes.

 

[chris667]

No good for conversion without disc brakes.

Your posts on this topic remind me of a certain other member on this forum who sounds a bit ridiculous because of his insistence that hub motors are all useless.

The fact is that Magura rim brakes are perfectly adequate for stopping an electric bike. In practical use for many applications there's no performance difference between them and discs - if you think they lack modulation it strikes me you've never ridden a bike with them.

If they weren't worth having, they wouldn't still be manufactured and even specified on lots of high end bikes, including some electric ones and even electric cargo bikes.

They're just another option.

I'd certainly rather have Magura rim brakes than the cable discs that my old eBike came with which were utter crap, and also the Deore cable discs I had on my old MTB about twenty years ago which were heavier than Maguras and also crap, and for that matter the Avid Juicy discs that were on my On-One Inbred which completely seized up over a winter. I am still annoyed at those - how much more would it have cost to make them with stainless parts?

 

[AndyBike]

I'd certainly rather have Magura rim brakes than the cable discs that my old eBike came with which were utter crap, and also the Deore cable discs I had on my old MTB about twenty years ago which were heavier than Maguras and also crap, and for that matter the Avid Juicy discs that were on my On-One Inbred which completely seized up over a winter. I am still annoyed at those - how much more would it have cost to make them with stainless parts?

So we can take it from this that you make poor choices when it comes to brakes

Your posts on this topic remind me of a certain other member on this forum who sounds a bit ridiculous because of his insistence that hub motors are all useless.

Just banter really(its me youre referring to)
Same banter we get when anyone mentions mid drives. That is banter, isn't it ?.

 

[chris667]

So we can take it from this that you make poor choices when it comes to brakes

Yes, I bought some bikes in the early 2000s that had really, really bad brakes. It was OK, the next one had Magura HS22s which were really, really good. I had that one for years!

Same banter we get when anyone mentions mid drives. That is banter, isn't it ?.

I don't know really. Banter should be funny and it should make something boring more interesting. This forum is about a subject I find interesting, but the banter is boring.

Honestly, I think most of what the regulars post on here is just inane nonsense that just makes it harder to find useful information.

And like many forums it's dying on its arse, because a group of people who want to use it for "banter" make it harder to use. It's a real shame.

 

[saneagle]

Your posts on this topic remind me of a certain other member on this forum who sounds a bit ridiculous because of his insistence that hub motors are all useless.

The fact is that Magura rim brakes are perfectly adequate for stopping an electric bike. In practical use for many applications there's no performance difference between them and discs - if you think they lack modulation it strikes me you've never ridden a bike with them.

If they weren't worth having, they wouldn't still be manufactured and even specified on lots of high end bikes, including some electric ones and even electric cargo bikes.

They're just another option.

I'd certainly rather have Magura rim brakes than the cable discs that my old eBike came with which were utter crap, and also the Deore cable discs I had on my old MTB about twenty years ago which were heavier than Maguras and also crap, and for that matter the Avid Juicy discs that were on my On-One Inbred which completely seized up over a winter. I am still annoyed at those - how much more would it have cost to make them with stainless parts?

It's rare for manufacturers to choose hydraulic rim brakes for their electric bikes these days, or any bike, but when they do, they choose the rims carefully considering how the rim is likely to wear. When guys retrofit them, they generally don't even think about their rim, nor how it's likely to wear rapidly in service and fail catastrophically.

Hydraulic rim brakes are usually an improvement when fitted to a non-electric bike, but aluminium rims are not hard enough to deal with the accelerated rim brake wear from the higher average speeds on an electric bike. Very soon, the owner would need to replace a rim, which requires a complete wheel rebuild that is likely to cost more than a reasonable disc brake donor bike.

I agree that cable disc brakes are pretty crappy too, but it's a 5 minute job and about £40 to replace them with good used hydraulic ones from Ebay. Upgrading cable disc brakes to hydraulic ones is the best bang-for-buck upgrade you can do on any bike.

For the same cost as a hydraulic rim brake upgrade, you can buy a suitable disc brake donor bike plus a hydraulic brake upgrade.

In conclusion, it's difficult to justify a hydraulic rim brake upgrade from a cost point of view. They're less safe due to the possibility of unexpected catastrophic rim failure, and they cause substantial inconvenience when you regularly need to replace rims as a pont of service. I would always advise people not to go that route unless there's no choice. People that have not even started their projects need to know and understand the facts so that they can make the appropriate choices.

If you want to practise your religion of worshiping rim brakes, I accept your freedom to choose whatever religion you want, but probably best that you don't try to force it on unsuspecting and naive forum members unless you give them all the facts, not just the single point that they stop quickly..

 

[chris667]

It's rare for manufacturers to choose hydraulic rim brakes for their electric bikes these days, or any bike, but when they do, they choose the rims carefully considering how the rim is likely to wear.

I don't think that is as much of an issue as you think it is. In the wrong conditions and with the wrong pads rims do wear out quickly but in day-to-day usage on utility and touring bikes on roads I don't think it comes into it at all.

I've only ever worn out rims on one bike, my Dawes Galaxy with its original wheels (Alesa 917s, Exage hubs, IIRC). I never did much offroad, but I do did sixteen miles a day on it for five days a week (commuting to work) for a few years. Even then they hadn't actually failed. I did rebuild them with stainless spokes when they were new though, and of course the hubs needed regreasing every so often. That bike had cantilever brakes which are supposed to be lethal now but I never really noticed it.